Value addition to wastes: photo/sono-catalytic and antimicrobial performance of nickel ferrite derived using iron tailing and Raney nickel catalyst processing wastes.

This research highlights a sustainable approach for the design and synthesis of a magnetic nickel ferrite (NiFeO) catalyst reutilizing industrial waste, specifically iron ore tailing and Raney nickel catalyst processing waste, by simple co-precipitation method. Transforming waste materials into high-performance catalysts, this study aligns with the principles of a circular economy, addressing both environmental waste and pollution. Structural characterization by X-ray diffraction (XRD) and microscopic (FESEM and TEM) revealed the formation of well crystalline nano ferrite with NiFeO nanoparticles with cubic spinel structure. The ferromagnetic behavior with saturation magnetization of 43 emu/g and low band gap energy (1.81 eV) of the prepared catalyst supported its magnetic separation and activity under visible light. EDX and XPS analysis confirmed the purity of the sample with the existence of desired elements/ions. The prepared catalyst demonstrated significant photocatalytic and sonocatalytic activity under visible light and ultrasonic waves, respectively. The catalyst efficiently degraded the Reactive Red 35 (RR35), a model dye contaminant, in its aqueous solution (20-40 mg/L) within 2 h of the reaction. Besides its pollutant for dye removal, the catalyst also exhibits remarkable antibacterial activity, achieving a fivefold faster E. coli disinfection rate in comparison to traditional catalysts. Overall, the results established a lab-scale method for the synthesis of ferrite nanopowder from solid industrial wastes and provided inputs for developing a combined photo-sonocatalytic process for the degradation of different persistent organic contaminants including dyes.